Other constants such as `machine.Pin.OUT` are defined on the class that
uses them, rather than at the module level. This commit makes that the
case for WLAN network interfaces, adding IF_xxx and SEC_xxx constants.
The SEC_xxx constants are named as such to match the `security` keyword
that they are used with. And the IF_xxx constants have IF as a prefix so
they are grouped together as names.
This scheme of putting constants on the class means that only the available
features (eg security configurations) are made available as constants. It
also means that different network interfaces (eg WLAN vs LAN) can keep
their own specific constants within their class, such as PHY_xxx for LAN.
Signed-off-by: iabdalkader <i.abdalkader@gmail.com>
